US7517581B2ExpiredUtilityA1

Semipermeable hydrophilic membrane

41
Assignee: PARKER HANNIFIN CORPPriority: Sep 26, 2003Filed: Sep 23, 2004Granted: Apr 14, 2009
Est. expirySep 26, 2023(expired)· nominal 20-yr term from priority
Inventors:John SimonettiIrina Vinarov
B01D 63/1031B01D 67/0016B01D 2323/42Y10T428/31971B01D 71/34B01D 61/145Y10T428/249953B01D 71/18Y10T428/249964B01D 2325/36Y10T428/249981Y10T428/3154B01D 69/08
41
PatentIndex Score
2
Cited by
134
References
39
Claims

Abstract

A hydrophilic semipermeable membrane can include a porous polymeric structure containing a blend of PVDF and hydroxyalkylcellulose. The membrane may be used for ultrafiltration. A method of making a hydrophilic semipermeable membrane can include providing a blend containing PVDF and hydroxyalkylcellulose, forming the blend into a porous polymeric structure, and purifying the porous polymeric structure.

Claims

exact text as granted — not AI-modified
The invention claimed is: 
     
       1. A semipermeable membrane, comprising:
 a porous polymeric structure comprising a homogeneous blend of PVDF and hydroxyalkylcellulose; wherein the membrane is hydrophilic. 
 
     
     
       2. The membrane of  claim 1 , wherein the hydroxyalkylcellulose is selected from the group consisting of hydroxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxybutylcellulose, hydroxypentylcellulose, and mixtures thereof. 
     
     
       3. The membrane of  claim 1 , wherein the hydroxyalkylcellulose comprises a mixed hydroxyalkylcellulose. 
     
     
       4. The membrane of  claim 1 , wherein the hydroxyalkylcellulose is selected from the group consisting of hydroxyethylcellulose, hydroxypropylcellulose, and mixtures thereof. 
     
     
       5. The membrane of  claim 1 , wherein the hydroxyalkylcellulose comprises hydroxyethylcellulose. 
     
     
       6. The membrane of  claim 1 , wherein the hydroxyalkylcellulose comprises hydroxypropylcellulose. 
     
     
       7. The membrane of  claim 1 , wherein the ratio of PVDF to hydroxyalkylcellulose in the porous polymeric structure is from about 20:1 to about 5:1. 
     
     
       8. The membrane of  claim 1 , wherein the ratio of PVDF to hydroxyalkylcellulose in the porous polymeric structure is from about 15:1 to about 7:1. 
     
     
       9. The membrane of  claim 1 , wherein the membrane is hydrophilic in the absence of a wetting agent. 
     
     
       10. The membrane of  claim 1 , wherein, when the membrane is dried, the membrane remains hydrophilic. 
     
     
       11. The membrane of  claim 1 , wherein the membrane is an ultrafiltration membrane. 
     
     
       12. The membrane of  claim 11 , wherein the membrane is in the form of a hollow fiber. 
     
     
       13. The membrane of  claim 11 , wherein the membrane is in the form of a flat sheet. 
     
     
       14. The membrane of  claim 13 , wherein one surface of the flat sheet is in contact with a porous inert substrate. 
     
     
       15. An ultrafiltration membrane, comprising:
 a porous polymeric structure comprising a homogeneous blend of PVDF and hydroxyalkylcellulose in a ratio from about 20:1 to about 5:1; wherein the membrane is hydrophilic and has a molecular weight cut-off from about 1,000 daltons to about 2,000,000 daltons. 
 
     
     
       16. The ultrafiltration membrane of  claim 15 , wherein the membrane is hydrophilic in the absence of a wetting agent. 
     
     
       17. The ultrafiltration membrane of  claim 15 , wherein, when the membrane is dried, the membrane remains hydrophilic. 
     
     
       18. The ultrafiltration membrane of  claim 15 , wherein the membrane has a molecular weight cut-off from about 3,000 daltons to about 1,000,000 daltons. 
     
     
       19. The ultrafiltration membrane of  claim 15 , wherein the membrane has a molecular weight cut-off from about 10,000 daltons to about 500,000 daltons. 
     
     
       20. The ultrafiltration membrane of  claim 15 , wherein the hydroxyalkylcellulose is selected from the group consisting of hydroxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxybutylcellulose, hydroxypentylcellulose, and mixtures thereof. 
     
     
       21. The ultrafiltration membrane of  claim 15 , wherein the hydroxyalkylcellulose comprises hydroxyethylcellulose. 
     
     
       22. The ultrafiltration membrane of  claim 15 , wherein the hydroxyalkylcellulose comprises hydroxypropylcellulose. 
     
     
       23. The ultrafiltration membrane of  claim 15 , wherein the membrane is in the form of a hollow fiber. 
     
     
       24. The ultrafiltration membrane of  claim 15 , wherein the membrane is in the form of a flat sheet. 
     
     
       25. The ultrafiltration membrane of  claim 24 , wherein one surface of the flat sheet is in contact with a porous inert substrate. 
     
     
       26. A filter for ultrafiltration, comprising:
 a semipermeable membrane comprising a homogeneous blend of a mixture of PVDF and hydroxyalkylcellulose and comprising a feed surface and a permeate surface; wherein the membrane is hydrophilic. 
 
     
     
       27. The filter of  claim 26 , wherein the membrane is in the form of a hollow fiber, and the feed surface is the outer surface of the fiber. 
     
     
       28. The filter of  claim 26 , wherein the membrane is in the form of a hollow fiber, and the feed surface is the inner surface of the fiber. 
     
     
       29. The filter of  claim 26 , wherein the membrane is in the form of a sheet. 
     
     
       30. The filter of  claim 29 , wherein the permeate surface of the membrane is in contact with a porous inert substrate. 
     
     
       31. The filter of  claim 29 , wherein the sheet is planar. 
     
     
       32. The filter of  claim 29 , wherein the sheet is pleated. 
     
     
       33. The filter of  claim 29 , wherein the sheet is spiral wound. 
     
     
       34. The filter of  claim 33 , further comprising a second semipermeable membrane comprising a blend of a mixture of PVDF and hydroxyalkylcellulose, wherein the second semipermeable membrane is hydrophilic. 
     
     
       35. The filter of  claim 34 , further comprising a feed fluid layer; wherein the permeate surface of each membrane is in contact with a separate porous inert substrate layer, and the membranes and the feed fluid layer are configured as an envelope having the feed fluid layer in the center of the envelope and having the porous inert substrate layers on the exterior of the envelope. 
     
     
       36. The filter of  claim 35 , further comprising a permeate transport layer; wherein the envelope is wound in a spiral, and the permeate transport layer is positioned between the porous inert substrate layers. 
     
     
       37. The filter of  claim 26 , wherein the filter is configured to flow unfiltered feed fluid across the feed surface of the membrane in a path that is tangential to the surface. 
     
     
       38. The filter of  claim 26 , wherein the membrane has a molecular weight cut-off from about 1,000 daltons to about 2,000,000 daltons. 
     
     
       39. An ultrafiltration membrane, comprising:
 a porous polymeric sheet comprising a homogeneous blend of PVDF and hydroxyalkylcellulose in a ratio from about 20:1 to about 5:1, and comprising a feed surface and a permeate surface; wherein the hydroxyalkylcellulose is selected from the group consisting of hydroxyethylceltulose, hydroxypropylcellulose and mixtures thereof and a porous inert substrate in contact with the permeate surface; wherein the membrane is hydrophilic in the absence of a wetting agent, and remains hydrophilic when the membrane is dried.

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